This invention discloses amorphous silicon/amorphous silicon-germanium NI1PI2N used in infrared position detectors, and light-pen based digital boards.
Infrared position detectors currently on the market, primarily consist of PIN diodes made from crystalline silicon. The structure of such detectors is designed chiefly for one-dimensional detection. Infrared detectors built with amorphous silicon or amorphous silicon-germanium alloy, have only a single detection function, detecting infrared, but not position. In 1991, L. C. Kuo et al. used a relatively thicker I layer as the absorption layer to detect infrared light (Materials Research Society Proc. Vol. 219, pp.783-789, 1991). In 1990, JYH-Wong Hong et al. put forward the Avalanche photo diode for use in infrared detectors (IEEE Quantum Electronics, Vol.26, No.2, pp.280-284, 1990). The Avalanche photo diode increases the detection efficiency of the infrared signal using a large reverse bias.
C. Y. Chen et al. suggested that in NI1PI2N infrared detector, the first NIP diode absorbs infrared light, and the second PIN diode amplifies the signal. (Appl. Phys. Lett. Vol.39, No.4, pp.340-342, 1981).
Although the aforementioned structure of infrared detectors can be used for visible light, using a crystalline silicon PIN to absorb infrared light, neither supports two-dimensional large-scale position detection, nor effectively prohibits visible light signals from being absorbed.
The infrared detectors that include an amorphous silicon-germanium alloy PINs, designed by L. C. Kuo et al., failed to prohibit visible light absorption and leading to inefficient detection. The Avalanche photo diode put forward by JYH-Wong Hong et al., generates an amplified Avalanche signal under a large reverse bias, can not prohibit visible light from absorption either. Despite possessing a structure similar to that of this invention, the NI1PI2N structure suggested by C. Y. Chen et al, follows a different principle and can not prohibit visible light from: absorption, because the front NI1P diode absorbs infrared light, whereas the rear diode PI2N amplifies the signal.
The primary purpose of the invention is to disclose the amorphous silicon/amorphous silicon-germanium NI1P2N used for infrared position detection. The material of the I1 layer absorbs visible light, and I2 layer absorbs infrared light. The suppression of the signal due to the absorption of the visible light and the increase in the signal due to the absorption of the infrared light, can be obtained by a NI1P diode under forward bias and the PI2N diode under reverse bias.
The second purpose of the invention is to disclose the manufacture method of amorphous silicon-germanium alloy. It is produced by modulating RF plasma with a square wave pulse and diluting hydrogen.
The invention can be modified in a number of ways. Illustrative examples are presented.